Firewall: Definition, How They Work and Why You Need One 

In construction terms, a firewall is something that limits the damage a fire can cause. Rather than letting the flames grow, spread, and consume everything they touch, a firewall encircles the area and contains the heat and smoke.

Computer versions work in much the same way.

A network firewall creates a barrier between your system and external sources. In essence, it keeps damage from the outside spreading and harming your valuable internal data.


How Firewalls Work

What Is a Firewall? 

Think of your servers, datasets, and resources as your company's treasure. You should do everything you can to protect it from snoops and thieves. A firewall helps you do just that. 

A firewall is made of software, hardware, or a combination of the two. No matter what it looks like or how it's made, your firewall should:

  • Inspect. Traffic both entering and exiting your system should be closely examined, byte by byte. 
  • Decide. You define a set of actions or characteristics you'll allow. The traffic is compared to your rules. 
  • Act. If the traffic adheres to your rules, it's allowed. If not, it's rejected. 

When functioning properly, a firewall blocks some kinds of harmful traffic while allowing the good work to move forward unimpeded. And it's important to remember that firewalls protect you from things your staff might do. 

Depending on how you configure it, your firewall could protect your:

  • Server. A hacker tries to move in and see or steal your data. A firewall blocks their access.
  • Client. Someone in your system gets a faulty email and tries to download an enclosed file. Your firewall blocks the download. 

These are critical protections that can keep you a step ahead of danger. A firewall makes them possible.

10 Types of Firewalls 

Almost every company in business today has a firewall. And every one of those companies has different needs, requirements, and assets to protect. 

When every company needs something a little different, the market to create new products explodes. These are just some of the firewall solutions you could choose from to protect your company:

  • Application Layer 7: Sort traffic based on its contents and its destination. Block any traffic based on rules you define. 
  • Connection tracking: Examine the conversation between two sources using knowledge of the IP addresses they've used before. 
  • Endpoint: Examine data packets against rules you've crafted. 
  • Network address translation (NAT): a NAT can hide individual IP addresses, blocking scammers from understanding how your server works. This solution is technically not a firewall, but behaves like one.
  • Next-generation: Tap into intrusion prevention, threat analysis, and more with one product. 
  • Packet filter: Rules dictate what packets must be examined and what should happen if a problem is found.
  • Web application proxy: Rules dictate how traffic works for one specific application. 
  • Stateful inspection: All activity within an open connection is monitored, and filtering rules dictate what should happen. 
  • Unified threat management: All activity in open connection is monitored, and the system also looks for evidence of virus attacks. 
  • Virtual: Traffic bouncing between physical and virtual networks is monitored. 

You may have one, some, or all of these types of firewalls in play as you protect your company. Firewalls can also be used for external applications. When a firewall is used to protect external properties, they are called “web application firewalls”.

Why Is a Network Firewall So Important?

Nearly 95 percent of companies have firewalls now, and most of them say these tools are a critical part of their infrastructure. Servers are made to connect, and the open transfer of information is part of almost every business model. If you don't have a firewall, it's time to get one. 

But setting up a firewall the right way isn't always easy. Create rules that are too strict, and your employees won't be able to complete important work. Conversely, if you make the rules too lax, you'll allow dangerous activity to happen right beneath your nose. 

A firewall isn't bulletproof either. Even hobby hackers understand how to get around simple firewalls so they can do as they please without impediment. Monitoring remains an important part of your work. If a breach happens, you can step in and stop it. 

But a firewall is an important and basic part of offering safety and security to your company, no matter the threats that come your direction. It's smart to have one. 

At Okta, we offer a trusted platform you can use to secure identity. Our tools allow you to offer both customers and staff an easy sign-in process and a secure experience.

We'd love to talk with you about our firewall component. Contact us today. 


How Many Firewalls Do You Need? (March 2009). TechTarget.

94 Percent of Organisations See Firewalls as Critical Infrastructure. (August 2018). eWeek. 

How to Get Around Your School or Workplace Firewall. (November 2019). Help Desk Geek.